Heating system



June 26, 1945.

HEATING SYSTEM Filed Feb. 3, 1941 H.- J. DE N. MOCOLLUM 4 Sheets-Sheet l Ji enfy Jp@1/%(& Zlzen June 1945- Hui DE N. MCCOLLUM' 2,379,016

HEATING SYSTEM Filed Feb. 3, 1941 4 Sheets-Sheet 2 FUEL 6UPPLY J1me 1945- H. J. DE N. MCCOLLUM 1 2,379,016

HEATING SYSTEM Filed Feb. 5, 1941 4 Sheets-Sheet s MM y .mmlllll June 25, 1945- H. J. DE N. MccoLLuM 2,379,016

HEATING- SYSTEM Filed Feb. 3, 1941 4 Sheets-Shet 4' airplane operation.

' perature in the airplane cabin,

Patente d'june 26, 1945 HEATING SYSTEM Henry J. De N. McCollum, Chicago, r11.;- Thelma McCollum exeputrix McCollum, deceased said Henry J. De N.

Application February 3, 1941, Serial No. 377,181 Claims. (Cl. 126-110) My invention relates generally to heating systems particularly suited for use in heating large Diesel operated trains, and the like.

Considerable difliculty has been experienced in devising a heating system to heat the cabins of airplanes and maintain them at a uniform temperature under the greatly varying conditions of In most previous heating systems used for this purpose, the engine exhaust gaseshave been used as a source of heat. In general, two types of systems are used. In the first, the exhaust gases are passed through a heat exchanger which directly heats the air passing into the cabin, and in the second, the exhaust gases are used to vaporize a liquid to form a vapor which is used to heat the air passing into .the cabin. In these previous systems, the amount of heat available varies widely and is greatly reduced when the engine is throttled down as in a long glide. Further, these heating systems are inoperative while the plane is on the ground' loading or unloading, and it is necessary to use. an independent source of heated air if the passenger compartment of the plane is to be heated while it is at the airport. An object of my invention is to provide an im-' proved, independently operated heating system for airplanes in which the above disadvantages are eliminated.

conveyances such as airplanes, trucks, buses,

the combustible mixture used in the heating system'may be supplied either by the supercharger of the airplane engine or by a separate heater carburetor;

Fig. 4 is a perspective drawing of a heater' which may be used in connection with the heat ing systems represented in Figs. 1, 2, and 3, and Fig. 5 is a transverse sectional view taken on the plane 55 of Fig. 4, illustrating the con- Another object of my invention is to provide an improved internal combustion'heating system for airplanes and the like which burns liquid fuel independently of the airplane motor, which is easily controlled ,to maintain auniform temwhich is simple easily installed, weight, .and rein construction, which may be and which is compact, light in liable in operation.

A further object is to provide an internal combustion heating system for airplanes and the like which will supply alarge volume of @air heated to a uniform temperature.

Other objects will appear from the following description, reference being had to the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation of the general arrangement of the various elements which comprise a form of my invention;

Fig. 2 is a partiallycross-sectional diagram of a modified form of my invention, particularly adapted for use in heating a supercharged airplane cabin;

Fig. 3 is a diagrammatic representation of a form of my improved heating system in which struction of a heating unit suited for use in the heater illustrated in Fig. 3.

Referring to Fig. 1, a source of power 10, preferably alight, compact, air-cooled, single cylinder internal combustion engine, drives a centrifugal blower It for forcing air through the heater 34 into the space to be heated and an air pump or blower l2, which may be of the positive displacement type, for supplying a combustible mixture of liquid fuel and air to the engine In and the internal combustion heater 34. Fuelis supplied from a fuel supply 20, through a fuel line ID, to a carburetor l6 which mixes fuel and air' in the proper proportions to forms. combuscombustible mixture through these conduits, respectively, to deliver combustiblemixture to the engine 10 and heater 34 in the proper proportion to heat the air passing through the heater to I the desired temperature.

Air passes from the atmosphere into the centrlfugal blower l4 where it is compressed and supplied to the inlet of the heater 34 througha conduit 38; A conduit 40, leading from the outlet of the heater 34, conveys heated air to the cabin of the plane. This conduit 40 is preferably branched to distribute the heat properly through the space to be heated. A pipe H conveys the exhaust gases of the engine ID to the atmosphere.

The products of combustion from the heating unit 34, are discharged through a conduit 42 which preferably terminates at a point adjacent the outer surface of the plane where the pressure is maintained below atmospheric pressure by the motion of the plane.

It is seen from the above arrangement that the rate at which combustible mixture is drawn from the carburetor may be controlled by adjustment of the valve 20. If the flow through the valve 20 is decreased, less combustible mixture passes through the by-pa'ss 24 and more combustible mixture is supplied to the heater 34 and the engine I0. This causes the engine I to operate the blower I4 at a greater speed to pass more air through the heater. Inasmuch as more combustible mixture is supplied to the heater, the heater delivers more heat to the air passing through it and the resulting temperature of the air in the conduit 00 remains relatively constant. Conversely, increasing the rate of flow through the valve 20 decreases the amount of air heated but does not substantially change the temperature thereof. From the foregoing, it is seen ,that the amount of heat supplied to the cabin may be adjusted by varying the rate that heated air passes into the cabin rather than by raising or lowering the temperature of the heated air. Therefore there is no danger of overheating the various parts of the heater assembly and an occupant of the cabin of the plane seated near a hot air outlet is not subjected to the discomfort of having an uncomfortably hot blast of air.

blown upon him.

In the embodiment shown in Fig. 2, a small,

light gasoline engine I02 drives a cycloidal blower I00 of sumcient capacity to supercharge the airplane cabin. One end of the crank shaft is provided with a pulley I00, around which a cord may be wound to crank the engine, and is connected to the shaft of the blower I00 by a flexible coupling I06. The other end of the motor shaft is provided with a small blower I04 which blows cooling air past the finned cylinder of the engine I02. The blower I00 draws air from the atmosphere, compresses it, and forces it through a conduit IIO to the inlet of the heatercasing II2. A conduit I20 supplies air under pressure from the outlet of the blower I00 to the inlet of a balanced carburetor I22. A compensating duct I26 connects the conduit I20 with the float bowl of the carburetor I22 to equalize the pressure thereon. Combustible mixture passes from the outlet of the carburetor through a conduit I30 and through a pair of intake manifolds I32 to the individual heating units I34. A conduit I35, provided with an adjustable valve I31 for regulating the rate of flow therethrouzh, supplies combustible mixture from the outlet of the carburetor I22 to the engine I02.

The products of combustion from the heatin units I34 pass into a pair of exhaust manifolds II8, which conduct them to an exhaust pipe II8 which discharges them, preferably at a pointedjacent to the outer surface of the airplane mainthe motion tained at subatmospheric pressure by of the plane. The engine exhaust discharges through an exhaust pipe I with a silencer I42, into the atmosphere.

An apertured plate I30, located in the casing outlet conduit I30, is proportioned to maintain a sufficient back pressure in in the event of any leakage in the heating units, the combustible mixture and the products of com bustion therefrom will not escape to the air .being heated. A pressure responsive valve of the type disclosed in my copending application Serial No. 373,751, flied January '9, 1941, may be substituted for the apertured plate I30. The conduit I38, which conveys the heated air to the I39, which is provided cabin of the plane, is preferably branched to secure an even distribution of heat.

A butterfly valve I50, located in the conduit I30, directly controls the rate cf-flow of combustible mixture into the heating units I24. The valve I31 in the conduit I30 controls the rate of combustible mixture supplied to the engine I02. By proper relative adjustment of the valves I31 and I00, the relative amounts of combustible mixture flowing through the conduits I00 and I30 may be regulated to heat the air passing from the heater to the desired temperature. The resistance of the various conduits may be so proportioned that the capacity of the conduits supplying combustible mixture to the heating units bears the proper relationship to the capacity of the conduits supplying combustible mixture to the where it is compressed. A manually operable three-way valve I00 controls the admission of engine, and either or both of the valves I00 and I3! may be eliminated. A check valve I40 is preferably provided in the conduit I20 to prevent backfiring of the combustible mixture and the products oi combustion into the air being heated.

A second butterfly valve I40 controls the rate of flow of air through the conduit I20 and there by controls the rate at'which combustible mixture is supplied to both the heater and the engine. Adjustment of the valve I40 does not affect the relative proportions of the amounts of combustible mixture supplied to the engine and to the heater; Thus, as valve I40 is closed to reduce the amount of combustible mixture supplied, the engine will operate the blower I00 more slowly and air will be passed through the heater ly reduced and the net result will be that the air passing through the heater will be heated to substantially the same temperature for all ed justments of the valve I40.

The heating system illustrated in Fig. 3 is much the same in construction and operation as the heating system shown in Fig; l. Illustrated in connection with the heating system is an airplane engine I08 having a supercharger and a supercharger casing I00. Combustible mixture is drawn by the supercharger from the airplane carburetor I80 into the supercharger casing I00 combustible mixture to the inlet conduit I0 of the blower I2. When the airplane is cruising,

. this valve may-be positioned to supply combustible, mixture under pressure from the supercharger casing I06 to the inlet of the blower I2. when the airplane engine is not in operation, or when it' is idling, the three-way valve I00 may be positioned so that the blower .I2 draws com- I bustible mixture through a conduit I04 from the passing heating system carburetor I0. Other portions of the apparatus correspond to similar portions described in connection with Fig. l, and are similarly numbered.

"When the airplane is operating at high altitudes-it is advantageous for the pressure of air through the heater and the combustible mixture passing into the heater to be greater with respect to atmospheric" pressure than when the plane is operating at, lower altitudes, so that the air in the airplane cabin is somewhat supercharged. This auses a greater load to be imposed upon the engine I0, inasmuch as the blower I4 and the pump I2 operate at a greater pressure differential between their respective inlets and outlets.

However, by positioning the valve I00 to supply combustible mixture under pressure from the airplane supercharger to the heating system, the load upon the pump I2 is substantially eliminated. The engine 10 Will then run faster and cause the blower I4 to suply air to the cabin at a greater pressure. The amount of combustible mixture used in the heating system is so small in relation to the amount of combustible mixture burned in the engine that the operation of the.

. heater and is secured thereto by screws 94, thereby holding the unit in its proper position. Combustible mixture is supplied to fittings 88, each fitting distributing the mixture to one series of heating units. Combustible mixture passes from these fittings 88, through tubes 90, to the individual heating units. The tubes 90 are preferably of equal length and diameter so that they have equal resistance to fluid flow and therefore supply equal quantities of combustible mixture to the variousunits.

The individual heating units may be of the general type disclosed in my prior Patents Nos. 2,191,173, 2,191,174, and 2,191,178, issued February 20, 1940. The casting 52 comprises a generally cylindrical bore 53, the walls of which are protected by a cylindrical liner 56 of a heat and corrosion resistant material, such as stainless steel or a ceramic composition, to form a combustion chamber 52. Combustible mixture flows from the tube 90, through an elbow-shaped passageway 64 formed in the projecting portion 66 of the casting 52, into a burner tube 62 which contains a loose packing 6i of metal wool. From the burner tube 62 the mixture flows past peripheral ports 58 formed in a bafiie 6b, which forms the inlet end wall of the combustion chamber 52, into the combustion chamber 52 where it is burned, An apertured ceramic plug 68, which serves as a reigniter in a manner more fully disclosed in my prior Patent 2,192,688, issued March 5,.1940, is located in the outlet of the combustion chamber. A heat exchanger casting it, having interconnected circuitous passageway it formed therein, receives the products of combustion from the combustion chamber 52-. A copper shell iii, provided with heat exchange fins tll, encloses the portion of the heating unit within the casing 50 and retains the heat exchanger casting It to the flanged casting d. The products of combustion pass from the outlet 96 through the circuitous passageways itinto the heater exhaust manifolds i it.

As shown in Fig. 4, the heating units may be arranged in two series of five units each, there being ten units in all. One electrically operated igniter 8d, which may be of the type disclosed in my prior Patent No. 2,177,114 issued October 24, i839, is'provided'for each series of units. The igniter is positioned to ignite the combustible mixture and start combustion in the end heating unit of the series. The combustion chambers are interconnected by flash-over tubes it through which flame travels from the combustion chamber of one unit to the combustion chamber of the next unit of the series. A thermostatic switch '12 is provided to control the energization of each igniter. These switches are electrically connected in series with the live terminal 95 of each igniter, the other terminal being grounded. The switches 12 are closed at lower temperatures, but are responsive to the temperature of the heater to open the igniter circuits when combustion has been established, thereby discontinuing the energizetion of the igniters 84'. A manually operable switch 92, in series with the thermostatic switches 12; connects and disconnects a source. of electric current 93 and the igniter circuit. This switch 92 is preferably arranged to be opened and closed incidental to opening and closing the'ignition switch of .the gasoline engine which operates the system.

In the operation of the system shown in Fig. i.

I the engine is cranked and combustible mixture is drawn from the carburetor It by the pump I2 and supplied to the engine It where it is bumed' to supply power to operate the system. The starting of the engine In is facilitated if the valves 26 and 30 are closed. The engine It] operates the blower M which draws air from the atmosphere and forces it through the heater 34 and through the conduit 60 to the space to be heated. The pump l2 also supplies combustible mixture through the conduit 32 to the heater 36 where it is burned to supply heat which heats the air passing through the heater. The products of combustion from the engine to and the heater 3t pass through conduits 8B and 42 respectively and are discharged at a convenient point, preferably adjacent the outer surface of the plane where the pressure is maintained below atmospheric by the motion of the plane.

In the operation of the device shown in Fig. 2,

the engine is cranked to operate the cycloidal blower Hill. The blower I00 draws air from the atmosphere, compresses it, and passes it to the balanced carburetor I22 where it is mixed with fuel to form a combustible mixture. The combustible mixture then flows from the carburetor l22, through the conduit I35, to the engine 32 where it is burned to provide power to operate the blower Hill. The starting of the engine it will be facilitated if the valve I is closed. Air compressed by the blower I00 also passes through the heater 36 and through the conduit tilt to the cabin of the plane. Part of the combustible mixture from the balance carburetor I22 is supplied to the heating units I36 of the heater 36 where it is burned to heat the air passing through the heater 3d. The pressure of the air within the heater 34 is maintained at a positive pressure with respect to the interior of the heating units 136 by suitable means, illustrated as an apertured plate its in the conduit 38. The products of combustion from the engine Hi2 and the heater ltd are discharged through conduits lid and iii-J respectively.

The embodiment shown in Fig. 3 operates in a manner similar to the embodiment shown in Fig. l and described in connection therewith. However, at high altitudes, it will be found advantageous to operate the three-way valve 21% so that combustible mixture is supplied to the heating system from the casing ltd of the supercharger of the airplane engine.

In the operation of the heater 35, shown in Figs.

- of the individual heating units. The igniter at in the end unit of each series starts combustion in the combustion chamber 01' thatunit. Flame for mixing fuel from then rapidly flashes through the fiashover tubes 1! and establishes combustion in the interconnected heating units of the series in rapid succession. The products of combustion flow from each combustion chamber 52, through ports '69 in each ceramic plug 68 into the circuitous passageways l4, heating the heat exchanger casting Ii hich, in turn, conducts heat to the exchange ill. The air passing through the heater comes into contact with these heat exchange fins and is heated. The products of combustion pass from the interconnected passageways 14 into exhaust manifolds I I8 and through an exhaust pipe to the atmosphere. It is to be understood that a different form of internal combustion heating unit may be substituted in the heater for the one specifically described above.

While I have shown and described particular embodiments of my invention, it will be apparent to those skilled in the art that my invention is not limited to particular constructions disclosed. I, therefore, wish to include within the scope of the following claims all constructions by which substantially the results of my invention are obtained by substantiallythe same or' equivalent means.

I claim:

- 1. In a heating system for airplanes and the like, the combination of an internal combustion heater having an air inlet and outlet and burning a combustible mixture of vaporized fuel and air, an internal combustion engine, a source ofair, a blower driven by said engine to compress air from said source, a fuel supply, carbureting means receiving fuel from said supply and mixing it with air to form a combustible mixture, a passage for conveying air under pressure from the outlet of said blower to the inlet of said heater,

through said last named passage, a passagefor supplying combustible mixture from said carburetor to said heater, and a passage for supplying combustible mixture from said carburetor combustion engine, a source of air, a blower driv-- en by said engine for compressing air from said source, a fuel supply, carbureting means for mixing fuel from said supply with air to form a combustible mixture, a passage for supplying air under pressure from said blower to said heater, a passage for conveying heated air from the outlet of said heater to the space to be heated, a passage for supplying air under pressure from said blower to said carburetor, a check valve to permit air to flow from the blower to the carburetor and to prevent airfrom flowing in the reverse direction, a passage for supplying combustible mixture from said carburetor to said heater, and a passage for supplying combustible mixture from said carburetor to said engine.

4. In a heating system for airplanes and the like,'the combination of an internal combustion heater burning a combustible mixture of fuel and air therein," a fuel supply, a source of air, a cara passage for conveying heated air from the outletof said heater to the space to be heated, a pas sage to supply air under pressure from the outlet of said {blower to the inlet of said carburetor, a passage for conveying combustible mixture from said carburetor to said heater, and a passage for conveying combustible mixture. from said carburetor .to said engine.

' 2. In a heating system for airplanes and the like, the combination of an internal combustion from said source, a fuel supply, carbureting means said supply with air to form a combustible mixture, a passage for supplying compressed air from the outletof said blower to the inlet of said heater, a passage coniiecting the outlet of said heater to the space to be heated, a passage for supplying compressed air from the outlet .of said blower to the inlet of said heater having; an air inlet and an outlet and burning -a mixture of vaporized fuel and air, an 4 internal combustion engine, a source of air, a blower driven by said engine for compressing air carburetor. a valve forregulating the rate of flow buretor receiving fuel from said supply and mixing it with air to'form a combustible mixture, an internal combustion engine, a' passage for conducting combustible mixture from said carburetor to said heater, a passage forconducting combustible mixture from said carburetor to said engine, and means driven by said engine to pass air from said source through said heater to be heated thereby and to supply air under pressure to said carburetor.

5. In a heating system for airplanes and the like, the combination of an internal combustion heater burning a combustible mixture of vaporized fuel and air, an internal combustion engine,

a source of air, a blower driven by said engine for compressing air from said source, a fuel supply, carbureting means receiving fuel fromsaid supply and mixing it with air to form a combustible mixture, a duct for conveying air under pressure from said blower to said heater, means for distributing the air heated by said heater into the space to be heated, a duct to supply air under pressure from said blower to the inlet of said carbureting means, a duct for supplying combustible mixture from said carburetor to said heater, a duct for conveying combustible mixture from said carburetor to said engine, and means for controlling the relative amounts of combustible mixture supplied to said heater and said engine, whereby said system may be caused to deliver air heated to the desired temperature.

- HENRY J. DE N. McCOLLUM. 

